The goal of the proposed project is to use a multimodal assessment strategy to gain a better understanding of the biological dysregulation that is a fundamental feature of posttraumatic stress disorder (PTSD). This will be done by examining the biologically understudied population of female rape and physical assault victims. The results will have implications for a greater understanding of the genesis of the disorder and for the efficacy of psychotherapeutic treatments. The biological dependent measures that have been selected comprise the significant biological alterations proposed from the most widely accepted animal model of PTSD, i.e., inescapable shock, and from previous research with combat veterans. In Study One, a prospective design will be used to collect data from a community sample identified through police and victim assistance agencies. This sample will consist of 60 women who were raped or physically assaulted. A matched comparison group of 25 non-PTSD subjects will be drawn from the community. Multi-modal assessments will be conducted on this sample at both 1 month postassault and 6-months postassault. Women will be assessed using: 1) a battery of self-report inventories on a laptop computer; 2) a clinician-based interview of PTSD (CAPS) and Mood Disorders (SCID I); 3) a low dose (0.5 mg.) dexamethasone suppression test; and 4) a psychophysiological laboratory assessment which will include measures of reactivity to trauma and neutral stimuli, acoustic startle response, stress-induced analgesia, and nonverbal/verbal behavior. A multimodal approach holds the greatest promise for uncovering complex interrelationships between biological parameters and between biological and psychological measures. In Study Two, which will be conducted concurrently with Study One, the multimodal assessment battery used in Study One will be employed to assess the efficacy of two promising psychotherapeutic treatments for PTSD: Prolonged Exposure (PE) and Cognitive Processing Therapy (CPT). Subjects will consist of 50 rape victims with PTSD who are seeking treatment. Half of the subjects will be treated with PE and half with CPT. Treatment subjects will be recruited from an ongoing clinical trial comparing CPT to PE. Assessments will be conducted immediately prior to treatment and at posttreatment. Results will have implications for PTSD diagnosis and treatment.